Automatic recovery device for pneumatic suspensions



1934- e. L. R. J. MESSIER 1,980,423

AUTOMATIC RECOVERY DEVICE FOR PNEUMATIC SUSPENSIONS Filed Dec. 19. 1928 Fig.1. Fig.2.

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g #Vl/ENTOR F Geo/ye Lav/ls Rene Jean fleas/er ATTORNEY UNITED STATES PATENT orFie AUTOMATIC RECOVERY DEVICE FOR PNEUMATIC SUSPENSIONS George Louis Ren Jean Messier, Montrouge, France Application December 19, 192 Serial No. 326,995 In France December 30, 1927 1 Claim. (Cl. 26764) The present invention has for object an autovalve it provided therebetween capable of openmatic recovery device for pneumatic or oleoing which is to allow the circulation of the lost pneumatic suspension of the undercarriage of an compressed fluid or of the oil from J towards e, airplane. but not in the reverse direction.

5 In fact it is known that the pistons of pneu- In these conditions, when the airplane is in 0 matic or oleo-pneumatic suspension of airplanes, flight, the reaction of the ground on the wheels as fluid-tight as they may be, let the fluid under being eliminated, the piston moves downwardly, pressure escape in the long run. compressing the air situated under its lower face,

The device forming the subject-matter of the until the total pressure exerted on this lower 10 present invention is adapted to ensure the autoface balances the total pressure exerted onits matio recovery of these losses. upper face, to which is added the weight of the Reference is made to the accompanying drawsuspended undercarriage: axle, wheels, etc. ing illustrating the invention, wherein similar Even when the supplementary weight correreference letters designate similar elements and sponding to the suspended parts is not taken into 16 wherein: consideration, it will be seen that the surface on Fig. 1 illustrates a vertical section of the pneuwhich the air compressed in the space 1 exerts matic suspension device with automatic recovits pres u is less a that Of the pp face of ery of the losses according to the invention. the piston. win to h presence of he rod 0! Fig. 2 illustrates a vertical section of the de- The air, occupying the space 7, reaches there- 20 vice with an abutment on the bottom of the fore, at the end of each taking-off, a unitary cylinder. pressure greater than that of the fluid in the Fig. 3 illustrates a vertical section of the de- Space 6; hence the valve It opens and, through vice With the abutment and an inlet valve in the the medium of the pipes g and i, the fluid lost bottom of the cylinder. in the space is carried by said compressed air Fig. 4 illustrates a modification of Fig. 1 as to above the piston, into the space 2. the placement of the valve between the spaces of Upon landi t VelVe h being 01 again, th li d the piston, by rising, tends to create a vacuum in The suspension apparatus for airplanes is conthe space 9, but all the fluid or all the oil which stituted by a cylinder a, integral with the fuselage had been able to flow under the piston hasbeen 30 and in which moves a piston b; this piston carries brought in the space e. a rod 0 rigid with the axle of the landing chassis The losses have therefore been wholly recovered or undercarriage; this rod passes through the in an automatic manner. lower wall of the cylinder through a stuffingt ey pp a the end of a long p box (1. that additional atmospheric air enters the space 5 The pressure of an initial load of fluid in the 1 through the stufiing-box d and that this air cushioning space e, above the piston, is regulated is delivered with the recovered fluid, upon flyin such a manner that the piston occupies noring ofi, into the space e. mally, when the airplane is on the ground, such If this phenomenon is repeated a number of an intermediate position in the cylinder, (for times, the quantity of air contained in the space 0 instance that shown in Fig. 1) that the air fille may become too great and give to the piston ing the closed space f, below the piston b, is then b a balancing position which is too low. This at substantially atmospheric pressure. may be prejudical to the operation of the ap- After a time, a portion of the fluid under presparatus.

sure which fills the space e (or of the oil which For avoiding this inconvenience, use may be covers the piston in the case of an oleo-pneumatic made of the device diagrammatically illustrated suspension) passes about the piston and is stored in Fig. 2.

in the space i below the piston. The pressure This apparatus is of the same general arrangein the space 2, it being of course understood that ment as that of Fig. .1, but a ring forming abutthe leakage about the piston is reduced by the ment it limits the downward movement of the use of suitable paclrings, will reach a high value piston at a predetermined distance from the lower only after a very long time as it will be easy to bottom of thecylinder.

maintain through the stuffing-box d a perfect This distance is so computed that, assuming fluid-tightness. the space I being filled with air at atmospheric The invention essentially consists in connectpressure in the position of the piston correspond- :5 ing the spaces e and f by pipes g and i and a ing to the apparatus on the ground, the down- 1 ward stroke of the piston, upon flying off, is stopped by the abutment is when the compression of the air of the space i is approximately equal to that of the air at the same momentin the space e.

It will then be understood that if the initial pressure in the space I is greater than atmospheric pressure (case of losses through the periphery of the piston), the pressure in the'same space, when the piston abuts against the abutment it, will be greater than that existing at the same moment in thespace e and the valve h by opening will ensure the recovery of the said losses.

The automatic adjustment of the position vof the piston canalso be ensured, even in the case of loss or leakage between the piston and the inner wall of the cylinder, for instance by'providing the lower bottom of the cylinder with an inlet air valve Z, opening from the exterior towards the interior (Fig. 3).

In these conditions, a raising of the initial balancing position of the piston causes a vacuum in f and hence an admission of air through the valve Z; the delivery of this air in the space e" will take place at the time of flying off, considering that, when the piston abuts against the abutment k, the pressure in the space f will then be greater than that existing at the same moment in the space e. I

The device thus completed ensures therefore the recovery of the losses in all conditions of leakage of fluids or of entrance of air, and at the same time, the automatic adjustment of the position of the piston.

The valve 71. instead of being placed outside the cylinder a, as shown in Figs. 1, 2 and 3, may be arranged in the body of the piston b, as shown in Fig. 4, the pipe or conduit 2' is then also provided in said piston b, thus greatly simplifying the construction of the device.

What I claim is:

A pneumatic or oleo-pneumatic suspension device for supporting an aeroplane body with respect to its under carriage, comprising in combination, a substantially vertical cylinder rigid with one of said two parts of the aeroplane and adapted to contain a predetermined constant quantity of fluid under pressure, a piston rigid with the other of said two parts and adapted to slide free 1y within said cylinder, a mass of fluid located above said pistonforming a supporting cushion when the aeroplane is resting on the ground, a conduit solely and directly interconnecting the upper portion of said cylinder through the side wall thereof with the lower portion of the cylinder directly through the bottom thereof and exof said conduit located adjacent the side of said cylinder for the purpose of allowing the fluid to 

